1. Technical Field
The present invention relates to a liquid crystal device with a fringe field switching (FFS) mode which is a transverse electric field switching mode.
2. Related Art
Presently, liquid crystal devices are widely used in electronic apparatuses such as cellular phones, portable information terminals, and personal digital assistants (PDAs). Among liquid crystal devices, there is known an FFS mode liquid crystal device in which first electrodes and second electrodes are disposed on one substrate with a dielectric film interposed therebetween, the second electrodes are each formed by a plurality of line-shaped electrode portions disposed parallel to each other with gaps interposed therebetween, and the first electrodes are formed by planar electrodes. In this case, as a switching element, a thin-film transistor (TFT), which is a three-terminal switching element, is used (for example, JP-A-2001-83540 (Pages 4 and 5, FIG. 3)).
As an active matrix type liquid crystal device, there is known a liquid crystal device which uses a thin-film diode (TFD) element, which is a two-terminal switching element, as a switching element for driving a plurality of pixels to be turned ON (white display) or OFF (black display). In addition, there is known a liquid crystal device which uses a thin-film transistor (TFT) element, which is a three-terminal switching element, as a switching element (for example, see JP-A-2003-29289 (page 5, FIG. 1)).
The liquid crystal device disclosed in JP-A-2001-83540 is a transverse electric field type liquid crystal device in which the first electrodes are disposed on one of a pair of substrates bonded by a seal member and the second electrodes are disposed on the other thereof. Wiring lines are electrically connected to the first electrodes and the second electrodes to supply necessary signals. In the liquid crystal device disclosed in JP-A-2003-29289, the second electrodes and the wiring lines for supplying signals to the second electrodes are disposed in different substrates and electrically connected to each other through conductive members disposed in an inner side of a seal member.
The FFS mode liquid crystal device disclosed in JP-A-2001-83540 can realize characteristics of a wide viewing angle and a high-contrast display, compared with a vertical electric field switching type liquid crystal device which is a popular type of liquid crystal device that operates in a twisted nematic (TN) mode.
However, in the liquid crystal device disclosed in JP-A-2001-83540, the TFT element, which is a three-terminal switching element, is used as a switching element for controlling a voltage applied to pixels. Accordingly, problems arise in that the configuration of the elements disposed on substrates is complex, manufacturing processes are complicated, and manufacturing cost is high.
Therefore, inventors have simplified the configuration of a transverse electric field type liquid crystal device using a TFD element, which is a two-terminal switching element, disclosed in JP-A-2003-29289. However, when an FFS mode liquid crystal device is configured using a TFD element, the plurality of second electrodes and the plurality of wiring lines electrically connected to the second electrodes are disposed on the same substrate. Such a configuration is different from that in the vertical electric field type liquid crystal device. Accordingly, the second electrodes may be short-circuited in accordance with the configuration of the wiring lines.
Such a problem is not limited to the case where a TFD element is used, but may also occur in the case where a TFT element, which is a three-terminal switching element, is used.
In order to avoid this problem, a configuration in which the wiring lines are electrically insulated from the second electrodes is necessary. However, if the electrical insulation configuration is provided only for the wiring lines and the second electrodes, the configuration of the liquid crystal device may not be sufficiently simplified. Moreover, if the electrical insulation configuration is provided, there may be restrictions on the configuration of the wiring lines and the electrodes on the substrate. Accordingly, the configuration of the elements disposed on the substrate may not be simplified.